The OP is about FB messenger, not WhatsApp, no ?!
_________________Apple passcode unlock + decrypted filesystem dump, Android user locks unlock + physical dump with decrypted userdata partition. We provide our services world-wide, but we reserve the right for choosing which tasks we take and which we deny!

Hello you can take a look at the DP 10 at www.datapilot.com
This is a great hand held device for acquisitions and viewing the data on the spot in real time. This device has built in screen mirroring so all apps that are on the phone can be mirrored and captured via the forensic device (no foot print is left behind). If you have any question you can contact myself as we are the manufacture and sole source provider in the US.
_________________(949) 789-8207- Directwww.secureview.uswww.datapilot.com
WHinkle @ susteen.com

Unfortunately it has nothing to do with apps data, there is no way to capture evidence with this device, which can't be displayed on the screen (for example sqlite entries with deleted flag or other artifacts at filesystem level).

Answering the OP, the issue can be solved well with a physical acquisition only. This can be done by using a signed eng boot + temporary root.
_________________Apple passcode unlock + decrypted filesystem dump, Android user locks unlock + physical dump with decrypted userdata partition. We provide our services world-wide, but we reserve the right for choosing which tasks we take and which we deny!

Hey Everyone,
I am using Magnet acquire but am only getting information like call logs, texts, pics. I was hoping to get app data, as I can see there are Facebook messenger messages as well as some other stuff. Thank You!

Do you have access to the target computer? Oxygen Forensic KeyScout offers the ability to seek and locate tokens and passwords saved on a computer as well as in various desktop Web browsers, like Internet Explorer, Google Chrome and Mozilla. The collected credentials can then be imported into Oxygen Forensic Cloud Extractor for immediate use

There are very few roots available for a Samsung S9. They are very new and Samsung purposely designs their phones to be difficult to root. Paraben Forensics is currently working on a free root capability that you will be able to access on their website. However, it is not yet available.